Osg 1400126205 Thread Forming Tap 1/4-20 Unc Cobalt Tin

Product Description

The OSG 1400126205 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming internal threads without cutting chips. It produces a 1/4-20 UNC right-hand thread using a modified bottoming chamfer with 2 to 2.5 chamfered threads, making it well suited for blind hole applications where thread depth control is critical. Constructed from cobalt high-speed steel and finished with a titanium nitride (TiN) coating, it delivers extended tool life in demanding materials. The overall length is 2.5 inches with a thread length of 0.594 inches and a tapping depth of 0.933 inches. This tap is installed by machinists and tool and die professionals in production and job shop environments.

This tap is rated for blind hole threading across a broad range of workpiece materials, including alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The modified bottoming chamfer allows thread forming to begin close to the bottom of a blind hole, reducing the unusable thread runout at the base. The H4 thread limit designation ensures consistent fit and tolerance control within standard UNC specifications. It is commonly used in CNC machining centers, drill presses, and tapping machines where a rigid or semi-rigid tapping setup is employed.

Key Features

• 1/4-20 UNC right-hand thread form, H4 thread limit for consistent tolerance control
• Modified bottoming chamfer with 2 to 2.5 chamfered threads for close-to-bottom blind hole threading
• Cobalt high-speed steel construction for improved heat and wear resistance
• TiN coating extends tool life and reduces friction during the forming process
• Chipless thread forming eliminates chip evacuation concerns in blind holes
• Compatible with material application codes P and N covering steels, stainless, and aluminum

Compatibility

Designed for blind hole thread forming in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Suitable for use in CNC tapping, drill press, and rigid tapping machine setups requiring a 1/4-20 UNC internal thread.

Installation Notes

Thread forming taps require a properly sized forming hole diameter, which differs from a standard cut-tap drill size — consult the tap manufacturer or a machinist reference for the correct forming hole size for 1/4-20 UNC. Use a tapping fluid or cutting oil appropriate for the workpiece material to reduce heat buildup and extend tap life. Ensure the spindle and tap are properly aligned before engaging the workpiece to prevent tap breakage. This tap does not produce chips, but the workpiece and tooling should be inspected for any material displacement or burring at the hole mouth after forming.